Does physics forbid such a device; a heat destroyer

[Darwin123]

I can see where you are coming from, but I don't think that answers the fundamentals for this problem.

It isn't a heat exchanger problem. The primary thought here is that the is machine converting heat to another form of energy, and can do this "perfectly", so any kinetic energy in the form of heat that hits the business end of this machine is converted to electric current. Converting energy from one form to another doesn't exactly "take" energy, but there are losses; so the question is does physics disallow the converting of increasingly up to (nearly)infinitely smaller quanta of kinetic energy.

Here's an example: let's say you you have some sort of exotic "gas", let's not worry too much about what the gas is, but it's some sort of monoatomic or subatomic ion or subatomic particle, the gas is contained within some sort of nano-mechanic system that is basically is series of nano-magnetic structures in a conductive matrix. Every time a ion passes through the field it would general some(very small) amount of current, and loss some of it's kinetic energy, as it successive passes through more nano-magnetic structures, it would lose all of it's energy. I can't find a specific law that would forbid this time of system.

Or am I missing something?

What you are missing is that there is no specific form of energy that is called heat. Furthermore, there is no specific form of energy called work. You can only use Carnot's formula if you know which packets of energy are called heat and which are called work.
In your example, you discriminated between kinetic energy that is heat and kinetic energy that is not heat. You claimed that the kinetic energy going in was heat. Furthermore, you are not telling us whether the electric current going out is also heat. Maybe the electric current going out is still heat.
Heat is energy that is transferred on a macroscopic scale by heat conduction. Heat is the temperature times the change in entropy. The designation heat has nothing to do with what form the energy takes on an atomic level.
I assume your machine absorbs heat by heat conduction. I will also assume that the electric current is work. By Carnot's theorem, it is impossible to turn all the energy absorbed by heat conduction into work.
So basically, your machine can't work because of the Second Law of Thermodynamics. If the second law is correct, you can't make a machine that automatically takes all the energy that comes into it by heat conduction and turns it into something else.
If the energy does not enter by heat conduction, then the energy is work. One form of work can be changed into another form of work. However, such machines already exist.
The weasel word here is "heat". "Heat energy" is conceptually ambiguous because heat is not a perfect differential. On an atomic level, heat is a mixture of many types of energy (kinetic, potential, etc.) So the minute that you say "kinetic energy that is heat", you run into an ambiguity.
Ahh, but that doesn't solve your literary problem. You are looking for some techno-babble that would sound plausible to a scientist. One thing you must avoid in a fantasy is ambiguity. Real life may be ambiguous, but at least it is real. A fantasy has to be extra specific to make up for the fact that it is a fantasy. Ambiguity can only weaken a SF story. I suggest that you describe your device in terms of entropy rather than heat energy.
Entropy is actually better defined than heat energy. Entropy is a perfect differential. Entropy acts a lot like an indestructible gas, where temperature is the pressure of the gas. I recommend that you hypothesize what the machine does to the entropy, rather than hypothesize what what the machine does to the heat energy. Whether or not your concept is viable, you will have avoided ambiguity.
The phrase "heat energy" is always ambiguous. Avoid it in science and in literature.

 

[Deeviant]

"A neat way around it seems to be the putting it in thermal contact with deep space idea."

This doesn't make any sense to me. You can not be in "thermal contact" with deep space, there is no contact with space, there is is no thermal interaction between the two at all(or am I missing some subtly here.) Or are you trying to just say put it in space and let it lose it's energy via black body radiation(I've asked this question several times regarding this and never got an answer). This would work equally well anywhere has sufficiently low ambient temperature, deep space has nothing to do with it.

 

[mfb]

Radiators can exchange thermal energy with deep space. As they are usually much warmer than 3K, their blackbody radiation as emission is a good description of this "exchange". Close to stars, you have to consider the stellar radiation, too.

 

[Dale]

You can not be in "thermal contact" with deep space, there is no contact with space, there is is no thermal interaction between the two at all.

Yes, you can, I don't know why you keep on making this incorrect assertion when I have corrected it multiple times. If you could not be in thermal contact with deep space then the Earth would be as hot as the sun since it couldn't get rid of all the heat that the sun dumps on it, and the Earth wouldn't cool off at night.

Or are you trying to just say put it in space and let it lose it's energy via black body radiation(I've asked this question several times regarding this and never got an answer).

While it is losing energy via blackbody radiation to deep space it is also gaining energy via blackbody radiation at 2.7 K from deep space. That is thermal contact with deep space.

 

[Deeviant]

Yes, you can, I don't know why you keep on making this incorrect assertion when I have corrected it multiple times. If you could not be in thermal contact with deep space then the Earth would be as hot as the sun since it couldn't get rid of all the heat that the sun dumps on it, and the Earth wouldn't cool off at night.

While it is losing energy via blackbody radiation to deep space it is also gaining energy via blackbody radiation at 2.7 K from deep space. That is thermal contact with deep space.

Multiple times I have asked you if you simply meant that an object loses energy due to black-body radiation, and you have never said "yes that is what I meant", this threw my off course. With further reading, I now understand how you are using the term, and I agree is used correctly and that there is "thermal contact" between objects and space, but I am still completely baffled by your responses. A spaceship is obviously always in thermal contact with space, it happens by default, and in the case, is to not nearly sufficient rate of heat loss, hence the whole idea of the thought experiment in which to create a process that has a faster rate of heat loss. Really, the term "thermal contact", though accurate, is really not helpful at all; speaking directly to black-body radiation rather that "thermal contact" immediately elicits the exact mechanism and even leads to easy finding of the exact mathematical description of the phenomenon (i.e. Planck's law of black-body radiation).

I think the main problem that I have digesting the rather consistent feedback from you guys is that objects already do what I what I want to accomplish here(albeit I want to accelerate the process somehow within the rules the universe has laid out): all objects turn their heat into electromagnetic energy and cast it out into space. It is trivially easy to see then, that converting heat(or whatever you would like to call it) into electromagnetic energy(in this case with 100% efficiency with no outside energy) does not break any laws of physics, this happens everyday; as you read this you are literally using converted heat energy that was converted into electromagnetic energy from the sun. So the cooling of an object by converting it's heat energy into electromagnetic energy without using additional energy is not against the laws of physics, it just isn't, if it was, we wouldn't be here right now.

 

[TobyC]

"A neat way around it seems to be the putting it in thermal contact with deep space idea."

This doesn't make any sense to me. You can not be in "thermal contact" with deep space, there is no contact with space, there is is no thermal interaction between the two at all(or am I missing some subtly here.) Or are you trying to just say put it in space and let it lose it's energy via black body radiation(I've asked this question several times regarding this and never got an answer). This would work equally well anywhere has sufficiently low ambient temperature, deep space has nothing to do with it.

Deep space isn't a perfect vacuum, I think I read somewhere that even in inter-galactic space there is about one hydrogen atom per cubic metre, and it therefore has a temperature associated with it from that.

Then of course it also has quite a bit of radiation in it, cosmic microwave background and light from stars, and you can associate a temperature to that as well, which should end up being the same temperature that the hydrogen gas is at. If you could get a machine which transferred heat from a system to the hydrogen gas for example, then that would be a way of cooling anything down to whatever the temperature of deep space is without having to put any energy in.

 

[TobyC]

I think the main problem that I have digesting the rather consistent feedback from you guys is that objects already do what I what I want to accomplish here(albeit I want to accelerate the process somehow within the rules the universe has laid out): all objects turn their heat into electromagnetic energy and cast it out into space. It is trivially easy to see then, that converting heat(or whatever you would like to call it) into electromagnetic energy(in this case with 100% efficiency with no outside energy) does not break any laws of physics, this happens everyday; as you read this you are literally using converted heat energy that was converted into electromagnetic energy from the sun. So the cooling of an object by converting it's heat energy into electromagnetic energy without using additional energy is not against the laws of physics, it just isn't, if it was, we wouldn't be here right now.

It's true that the energy we use comes from the sun, but it isn't converted from heat to work at no cost. The sun's radiation is at a higher temperature than the Earth, and that is what allows the conversion to happen, you always need a cooler reservoir if you want to convert heat to work, and your post made it sound like you wanted to build your machine without a cooler reservoir.

It now sounds like you want to place your machine on a spaceship in deep space, I didn't realize that before, in which case it is much easier to see how you could put things in contact with space to cool them down. In fact, that will happen anyway. If you have a spaceship in inter-galactic space, I imagine the problem will not be cooling stuff down, but rather keeping yourself warm. If you are within the solar system though you have to be more careful because then radiation from the sun is at quite a high temperature and your ship will absorb that.

So the cooling of an object by converting it's heat energy into electromagnetic energy without using additional energy is not against the laws of physics, it just isn't, if it was, we wouldn't be here right now.

No, it is really against the law of physics, it just is. You have to be careful what you mean by electromagnetic energy though, electromagnetic energy can still be heat energy, as people have pointed out. But either way, you still can't do it for free. If the electromagnetic energy you're getting out is in the form of heat then you can do it but there needs to be a colder reservoir to dump the electromagnetic heat energy in. And if you want all of the electromagnetic energy in a form you can get work from, like the form that could power a computer, then you just can't do it at all.

Some of the language here is getting confusing but I'll try to be clear what I am saying: "It is impossible to build a refrigerator that does not need to be powered".

 

[Dale]

Multiple times I have asked you if you simply meant that an object loses energy due to black-body radiation, and you have never said "yes that is what I meant", this threw my off course.

It is not just radiating blackbody radiation to space, it is also receiving blackbody radiation from space. That is why the phrase "thermal contact" is used rather than "losing energy due to blackbody radiation". It misses the other half of the physics (besides being wordy).

In any case, I was very clear even back in post 10 that the mechanism of heat transfer was via radiation. If you had spent less time telling me that I was wrong and making me repeat and re-justify my statements then maybe you would have cleared up your confusion faster. You act as though I have been the impediment to communication when, in fact, it is your continued desire to correct me and tell me what I am doing wrong that slows communication by making me waste time defending my statements rather than helping you learn. This post is another great example.

 

[Deeviant]

It is not just radiating blackbody radiation to space, it is also receiving blackbody radiation from space. That is why the phrase "thermal contact" is used rather than "losing energy due to blackbody radiation". It misses the other half of the physics (besides being wordy).

The 2.7k is inconsequential, it might as well be absolute zero for the purposes of a mechanism trying to dump the heat from a fusion reactor, it's a rounding error; it is pedantic.

I still would like to know why if I take what is being said in this thread to heart, I would have to conclude my very existence is barred by physics. I asked if it was possible to convert heat energy into some other form, without using any additional energy and further more if such a mechanism could be used to cool an object; the resounding answer is: no it violates physics. If it violates physics, why does it happen today, right now, in a absolutely massive scale?

 

[Muphrid]

Just what is it that you think converts heat energy into another form without taking energy to do so?

 

[TobyC]

I still would like to know why if I take what is being said in this thread to heart, I would have to conclude my very existence is barred by physics. I asked if it was possible to convert heat energy into some other form, without using any additional energy and further more if such a mechanism could be used to cool an object; the resounding answer is: no it violates physics. If it violates physics, why does it happen today, right now, in a absolutely massive scale?

You can remove heat from a system (and possibly convert it to some other useful form) but then one of two things has to happen:

1) You put more energy in by doing work to power it (like how a fridge works).

2) You have a colder reservoir handy to dump some heat in (like how putting an ice pack on something, or a car engine, or a fusion reactor works).

If the surroundings of a car were the same temperature as its engine then it couldn't work.

Nothing going on in the universe today violates this rule as far as we know. What examples were you thinking of?

 

[Dale]

I still would like to know why if I take what is being said in this thread to heart, I would have to conclude my very existence is barred by physics. I asked if it was possible to convert heat energy into some other form, without using any additional energy and further more if such a mechanism could be used to cool an object; the resounding answer is: no it violates physics. If it violates physics, why does it happen today, right now, in a absolutely massive scale?

Nobody ever said that. We said that you could do that, it is called a heat engine, it requires a cold reservoir, and the efficiency is limited by the Carnot efficiency limit. Heat engines don't violate physics and they happen on an absolutely massive scale.

 

[Deeviant]

Nobody ever said that. We said that you could do that, it is called a heat engine, it requires a cold reservoir, and the efficiency is limited by the Carnot efficiency limit. Heat engines don't violate physics and they happen on an absolutely massive scale.

You can't convert heat into any other form of energy freely without putting something (energy not in the form of heat) in. It is impossible for any machine to just take heat from a reservoir at a single temperature and convert it into work, that's one way of stating the 2nd law of thermodynamics.

Single reservoir: The Sun, which has for the purposes of this example a "single temperature". The sun's heat is converted directly into em radiation , the photon travels from then sun to the Earth then strikes a solar panel knocking an electron into the conduction band and creating current, the current does some work. No outside sources of energy were used. No laws were violated. The heat energy was converted directly into another type of energy, and in this cause, did do work.

 

[TobyC]

Single reservoir: The Sun, which has for the purposes of this example a "single temperature". The sun's heat is converted directly into em radiation , the photon travels from then sun to the Earth then strikes a solar panel knocking an electron into the conduction band and creating current, the current does some work. No outside sources of energy were used. No laws were violated. The heat energy was converted directly into another type of energy, and in this cause, did do work.

The solar panel is at a lower temperature than the sun, that's why it works. The solar panel is the second reservoir. If the solar panel was at the same temperature as the sun it wouldn't work. In any example you come up with you'll find there is always some object in there which has a lower temperature than what you're extracting heat from, and that is crucial, unless you want to put energy into power it.

The solar panel isn't actually essential in that particular example, heat is being removed from the sun as radiation whether the solar panel is there or not, just not as useful work, it stays as heat. In that case though the second reservoir is space, filled with hydrogen and an EM field at a very low temperature.

 

[Whovian]

Yes, but (I think) this relies on the solar panel being "cooler" than the Sun.

 

[Dale]

Single reservoir: The Sun, which has for the purposes of this example a "single temperature". The sun's heat is converted directly into em radiation , the photon travels from then sun to the Earth then strikes a solar panel knocking an electron into the conduction band and creating current, the current does some work. No outside sources of energy were used. No laws were violated. The heat energy was converted directly into another type of energy, and in this cause, did do work.

You do realize that the solar panel is colder than the sun, the hot sun transfers thermal energy to the cold panels, and the efficiency is much lower than the Carnot limit, right? This is a great example of a heat engine.

 

[Deeviant]

First of all, let me thank everybody here for providing valuable insight and taking time to contribute to this thread, I do very much appreciate it. And now I will jump back into it,

You do realize that the solar panel is colder than the sun, the hot sun transfers thermal energy to the cold panels, and the efficiency is much lower than the Carnot limit, right? This is a great example of a heat engine.

Even if such a process followed Carnot efficiency laws, it has absolutely no bearing on the first question: can heat be converted into another form of energy and thus be effectively purge heat from a system without some proportional outside energy being used.

So, the original question is can an object be cooled by converting it's heat into another form of energy, without the need to spend energy for the conversion, and can this be done to cool it down to some lower limit. The consensus was that it could not; that it was against the rules of physics, except that this is exactly what an object does all by itself when left by it's own accord in space: a object will convert all of it's internal energy into electromagnetic energy, cooling itself off to some lower limit(in this case stasis with the background radiation).

So I guess the question as it currently stands is not: can thermal energy be removed from an object without expending energy, as this is a foregone conclusion via black-body; but if physics really does some bar it from somehow artificially increasing the rate in which this happens. One trivial way to do this is to simply increase the surface area of object, but is that the only way.

 

[Drakkith]

I don't think the issue is in converting heat to EM energy, it is converting that EM energy to work that is the issue.

 

[Dale]

So, the original question is can an object be cooled by converting it's heat into another form of energy, without the need to spend energy for the conversion, and can this be done to cool it down to some lower limit. The consensus was that it could not; that it was against the rules of physics

No, the consensus was that converting heat to another form of energy is what a heat engine does, that it requires thermal contact with a cold reservoir (like deep space), the lower limit is the temperature of the cold reservoir, and that the efficiency is limited by the Carnot efficiency.

Where do you think anyone has said otherwise?

 

[Deeviant]

No, the consensus was that converting heat to another form of energy is what a heat engine does, that it requires thermal contact with a cold reservoir (like deep space), the lower limit is the temperature of the cold reservoir, and that the efficiency is limited by the Carnot efficiency.

Where do you think anyone has said otherwise?

In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work

A heat engine coverts thermal energy to mechanical work. It is simply wrong to continue to insist anything to do with thermal energy is a heat engine. Especially since in this case ending up with usable work is not at all required. Even if we did want to do work, who cares, the primary concern is to dump the heat and whatever work we get out of it is icing on the cake. I repeat, the question here is how quickly and efficiently does physics allow us to remove heat from an object. Nature has already provided us with a perfect example via black-body radiation, but does physics bar anything faster and more efficient.

As far as you're question, it is has been stated earlier in this thread that in order to pull heat out of mass, one must expend outside energy, this is false. Another claim was that pulling heat out of an object and converting into electromagnetic energy violates entropy laws, this is also false, black-body radiation does this already. Other statements insist that Carnot efficiency has something to do with the fundamental question I posed(I admit even I mentioned it in my OP), but as this discussion has progressed, it is now obvious that Carnot efficiency has nothing to do with it.

The question is, is a theoretical method to convert heat into EM in a method similar to black body radiation but faster.

 

[Drakkith]

There is no machine that can take thermal energy and convert it into another form of energy without losses. A simple object emitting black body radiation is not a machine.

The question is, is a theoretical method to convert heat into EM in a method similar to black body radiation but faster.

Sure. You can use energy and pump the heat from one location to another, with the end location being hotter than the source. Otherwise I don't believe you can make it any faster without expending energy.

 

[philrainey]

If one had a nuc reactor burning as hot as the surface of the sun and if there were materials that could withstand these tempertures. Could one drop a sphere into the burning mess that is in a complete vaccum. And if one had solar panels that could withstand the temperture could one have a sphere surrounded by them within the sphere in the nuc reaction receiving radiation from the hot bigger sphere surface and converting it to electricity without any heat been dumped in a cold sink?

 

[Drakkith]

If one had a nuc reactor burning as hot as the surface of the sun and if there were materials that could withstand these tempertures. Could one drop a sphere into the burning mess that is in a complete vaccum. And if one had solar panels that could withstand the temperture could one have a sphere surrounded by them within the sphere in the nuc reaction receiving radiation from the hot bigger sphere surface and converting it to electricity without any heat been dumped in a cold sink?

We don't have these materials so it isn't possible. All machines that convert energy to something else will have losses. The cold sink WILL heat up.

 

[TobyC]

First of all, let me thank everybody here for providing valuable insight and taking time to contribute to this thread, I do very much appreciate it. And now I will jump back into it,
Even if such a process followed Carnot efficiency laws, it has absolutely no bearing on the first question: can heat be converted into another form of energy and thus be effectively purge heat from a system without some proportional outside energy being used.

So, the original question is can an object be cooled by converting it's heat into another form of energy, without the need to spend energy for the conversion, and can this be done to cool it down to some lower limit. The consensus was that it could not; that it was against the rules of physics, except that this is exactly what an object does all by itself when left by it's own accord in space: a object will convert all of it's internal energy into electromagnetic energy, cooling itself off to some lower limit(in this case stasis with the background radiation).

So I guess the question as it currently stands is not: can thermal energy be removed from an object without expending energy, as this is a foregone conclusion via black-body; but if physics really does some bar it from somehow artificially increasing the rate in which this happens. One trivial way to do this is to simply increase the surface area of object, but is that the only way.

No one has ever said that it is impossible to remove heat from something without doing work, just that you need something colder for that to happen, then it happens by itself! Just put a hot thing next to a cold thing and watch the heat leave the hot thing, you can even get some useful work out of it.

Your post seemed to want to cool something down without having anything colder to dump the heat in. It is impossible to do that without putting energy in. DaleSpam came up with the neat idea of using space as your colder thing, putting the thing in contact with deep space, and if your machine is on a spaceship in deep space then that will be even easier. Like I said, the problem in that case is likely to not be cooling stuff down but keeping yourself warm.

Other statements insist that Carnot efficiency has something to do with the fundamental question I posed(I admit even I mentioned it in my OP), but as this discussion has progressed, it is now obvious that Carnot efficiency has nothing to do with it.

Carnot efficiency has everything to do with it, it tells you how much energy you have to put into take heat from a colder body and move it to a hotter body (which is what your machine will have to do if you don't have a colder reservoir handy) and importantly that energy is non-zero, it also tells you how much work you can get out if you're moving heat from a hot body to a cold body, but you don't seem to care about getting useful work out, just removing the heat. It also tells you that converting heat entirely into a 'useful' form of energy is impossible.

 

[TobyC]

If one had a nuc reactor burning as hot as the surface of the sun and if there were materials that could withstand these tempertures. Could one drop a sphere into the burning mess that is in a complete vaccum. And if one had solar panels that could withstand the temperture could one have a sphere surrounded by them within the sphere in the nuc reaction receiving radiation from the hot bigger sphere surface and converting it to electricity without any heat been dumped in a cold sink?

No that would only work while the solar panels were colder than the hot sphere. I'm not sure how solar panels work so I can't tell you exactly why it breaks down when the solar panels heat up, but once everything is at the same temperature (which will eventually happen), you can no longer get any useful energy out of the heat in the reactor.

As the panels approach the temperature of the reactor they become less and less efficient (meaning more of the energy they absorb goes into heating them up rather than producing electric current).

 

[Dale]

In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work

A heat engine coverts thermal energy to mechanical work. It is simply wrong to continue to insist anything to do with thermal energy is a heat engine.

The second law of thermodynamics is about entropy. The point of talking about mechanical work is that it has no entropy. If you convert thermal energy to any other form with 0 entropy then Carnot's efficiency limit applies. It can be derived in a couple of lines directly from the second law of thermo and the definition of temperature, regardless of the actual form of the 0-entropy energy.

Especially since in this case ending up with usable work is not at all required. Even if we did want to do work, who cares, the primary concern is to dump the heat and whatever work we get out of it is icing on the cake. I repeat, the question here is how quickly and efficiently does physics allow us to remove heat from an object. Nature has already provided us with a perfect example via black-body radiation, but does physics bar anything faster and more efficient.

That isn't the question posed in the OP, but if your concern is merely to dump the heat then that is simply heat transfer, not a heat destroyer. In space the only mechanism of heat transfer is radiation. Heat transfer still requires a cold reservoir in order to follow the second law. Luckily, 2.7 K is a pretty cold cold reservoir for most purposes.

it is has been stated earlier in this thread that in order to pull heat out of mass, one must expend outside energy, this is false ... Another claim was that pulling heat out of an object and converting into electromagnetic energy violates entropy laws, this is also false

Please quote these false claims exactly, I think you are just misunderstanding or misquoting.

The question is, is a theoretical method to convert heat into EM in a method similar to black body radiation but faster.

This question has already been answered in post 25. EM radiation has entropy, so if you radiate with any spectrum other than a black-body you will reduce the entropy which will involve the second law of thermo. In the limit of a very low entropy spectrum, like a laser, you can radiate a lot of energy quickly, but Carnot's limit applies.

 

[Dale]

I'm not sure how solar panels work so I can't tell you exactly why it breaks down when the solar panels heat up

Roughly speaking there is a "band gap" between different parts of the semi-conductor. When a photon with energy higher than the band gap hits the semi-conductor then it can push an electron across the gap and generate a current.

As solar panels heat up, the electrons in the semi-conductor become more energetic, to the point where they posess enough thermal energy to jump the band gap. The problem is that with thermal energy they jump both directions. So what happens is that the energetic photon is absorbed, which pushes one electron across the band gap, but instead of generating a current a thermal electron just jumps backwards across the band gap.

This actually happens at much lower temperatures than thermal equilibrium. Keeping solar panels cool is a major design consideration wrt efficiency.

 

[Dale]

Just to put some numbers on this. Suppose that the heat source is pretty hot, producing heat at 1000ºC (1273 K). And suppose further that the device is in thermal contact with deep space, as I suggested, and so it is using deep space as the cold reservoir (2.7 K). So the Carnot efficiency is 1-Tc/Th = .998. This means that for every 1 MW of heat produced, the device could capture 998 kW as work (or other low entropy forms of energy) and would have to dump 2 kW to deep space to satisfy the second law of thermo.

You can use the law for radiative power transfer for a black body, which is \dot{Q}= \sigma (T_h^4-T_c^4) A. So to radiate 2 kW at 1273 K to a bath of 2.7 K requires an area of .014 m².

You can just scale those numbers up by however many MW you expect your power plant to produce.

The technological advances would be to use deep space as the cold reservoir while radiating at the hot temperature. That isn't something we could do now, we would use a radiator as the cold reservoir which would be at an intermediate temperature between 1273 K and 2.7 K, reducing the maximum efficiency of the engine and increasing the surface area required to radiate. But that would be the limit of what is possible according to the laws of physics as we know them, so that would be the limit of what you could get away with using "future tech" but not breaking the laws of physics.

 

[mfb]

So, the original question is can an object be cooled by converting it's heat into another form of energy, without the need to spend energy for the conversion, and can this be done to cool it down to some lower limit.

Yes, if you have access to a cooler object (like space) and transmit a fraction of this energy to the cooler object. The required fraction depends on the temperature ratio.

The question is, is a theoretical method to convert heat into EM in a method similar to black body radiation but faster.

It is possible to be faster than low-temperature radiators alone. You can use the temperature difference between "hot object" and radiators: A part of the energy has to go to the radiators, another part can be used to do something else - for example, power a laser which additionally emits energy. However, a higher temperature of the radiators would do the same (where the temperature of the hot object is the ideal value).

@DaleSpam: You already need contact to the 2.7K-bath to extract 998kW. You cannot get this and feed a 1000°C-surface with the remaining 2kW. Otherwise you could use this 1000°C-surface again, and extract .998 of the 2kW... you see the problem?

 

[Dickfore]

Anyways, the question is this: can a "heat destroyer" be made?

As I define it, this device takes simply converts heat into some other form of energy, either EM or perhaps electricity. Of course, this can already be done in many ways today, but what we're talking about is a matter of degree. The amount of power it generates is not important, nor is the efficiency, but the important part is it can do so "infinitely" i.e. you turn the device on and it brings itself to near absolute zero, I suppose a somewhat higher minimum cap is ok. Another limitation is, other than the heat, it can't be fed any other energy, except maybe for some control or other higher level stuff, but the key here is it's not like you have to feed this thing a huge amount of energy for it to work, it just "eats" the heat.

My only lead is the carnot's work, perhaps the formula making clear that close delta T's make for very little work.

Your lead is wrong. Carnot's Theorem was proven by using the second law of thermodynamics.

The machine you are describing is exactly as the one in the Kelvin formulation of the second law.

So, the answer is that it is impossible!